Hold back means



Feb. 3,1970 J. J. sH uTTLEwoR H 3,493,094

. HOLD BACK; MEANS Original Filed Dec. 16. 1965 6 Sheets-Sheet l E DINVEMUR.

' E JAMES J. Suumswonm BY A 4/ lorry 5, E

Feb. 3, 1970 J. J. SH UTTLEWORTH 3,493,094

7 HOLD BACK MEANS 6 Sheets-Sheet 5 Original Filed Dec. 16, 1965 BKKWARDMQVEMENT GFCMS REMOVE!) JAM Fig.8.

INVEIVTOIZ. JAMES J. Suunuwom'u Feb. 3, 1970 J. J. SHUTTLEWORTH3,493,094

HOLD BACK MEANS Original Filed Dec.

6 Sheets-Sheet 4 mmun Jmss J. Sum-rumour a S l 8- United States PatentUS. Cl. 19820 1 Claim ABSTRACT OF THE DISCLOSURE An endless type beltconveyor. A hold back assembly including vertically parallel guide wallspositioned over and transversely across the conveyor. S'Wingable stopmeans mounted on the down stream end of the guide walls.

This is a division of application Ser. No. 514,205 filed Dec. 16, 1965,now Patent No. 3,386,224.

The present invention relates to a case packer adapted for automaticallypacking cans, glass jars, bottles and other objects in a case or box andto certain subcombinations thereof.

Various types of apparatus have been conceived for packing objects inboxes. These apparatus have not been completely satisfactory in allrespects. For example, some case packers require that vacuum cups beused to transport objects horizontally. Such horizontal transport tendsto shake loose the objects interfering with the operation of theapparatus. Consequently, one object of the present invention is toprovide a case packer so constructed that objects are moved by vacuumcups in only a vertical direction.

A case packer might include a platform, a frame, an object conveyormounted on the frame for conveying objects onto the platform, means formoving the platform away from a first position, and a hold back assemblymounted on the frame for stopping objects moving on the conveyor whilethe platform is away from the first position. The hold back assemblyincludes vertical parallel guide walls positioned over the objectconveyor and extending in the direction of movement of the objectconveyor for guiding objects into parallel lines, a plurality ofvertical doors hingedly mounted on the respective guide Walls toward thedirection of movement of the object conveyor, the doors being swingablebetween a first door position in which they extend in alignment with theguide walls and a second door position in which they extendperpendicularly to the guide walls and across the object conveyor, thedoors having a dimension between their proximal and distal ends which islong enough to prevent passage of objects between the door and the guidewall toward which it extends but short enough to permit the doors toswing to the second door position without blocking the objects.

The full nature of the invention will be understood from theaccompanying drawings and the following description and claim.

FIG. 1 is a front elevation of a case packer embodying the presentinvention.

FIG. 2 is a top plan view of the case packer of FIG. 1.

FIG. 3 is an end elevation of the structure of FIGS. 1 and 2.

FIG. 4 is an enlarged vertical section taken along the line 4--4 of FIG.2 in the direction of the arrows.

FIG. 5 is a vertical section taken along the line 7-7 of FIG. 4 in thedirection of the arrows.

FIG. 6 is a somewhat schematic top plan view of the object conveyerforming a part of the present invention.

FIG. 7 is a fragmentary enlarged top plan view of a portion of thestructure illustrated in FIG. 2. i

3,493,094 Patented Feb. 3, 1970 "ice FIG. 8 is a fragmentary perspectiveview of a gate forming a part of the structure illustrated in FIG. 9.

FIG. 9 is an enlarged fragmentary side elevation taken from the rightside of the apparatus as viewed in FIG. 3 with a cover plate removed toshow .internal operating apparatus.

FIG. 10 is a perspective fragmentary view of the operating portions ofapparatus making up the box conveyer of the present invention.

FIG. 11 is a perspective view of a can or object platform or pan forminga part of the subject case packer.

FIG. 12 is a somewhat schematic view of the hydraulic circuit of thepresent invention.

FIG. 13 is a schematic view of the electrical circuit of the presentinvention.

GENERAL OPERATION Referring now more particularly to the drawings, thereis illustrated a case packer 10 which includes a frame 11. Mounted uponthe frame 11 is a box conveyer 12 and a can or other object conveyer 13.Boxes are placed in the Opening 15 on the box conveyer 12 and moveinwardly to a position beneath the can conveyer 13. The boxes are thenmoved leftwardly as viewed in FIGS. 1 and 2 until they reach a positionbeneath a vertically movable vacuum head 16. The vacuum head 16functions to lift a pattern of cans and then to move the cans downwardlyinto a respective box positioned beneath the vacuum head 16 and on thebox conveyer 12.

The objects or cans moving on the conveyer 13 are guided into parallellines by means of a plurality of guide elements 17 of varying lengths,each of said guide elements being fixed to a pair of mounting members 20and 21. The mounting members are slidable upon a pair of horizontallyextending rods 22 and can be adjusted at any desired position on saidrods 22 by manipulation of cap screws 25. The rods 22 are fixed to theframe 11. When the guide members 17 are positioned, as shown in FIGS. 2and 3, the machine is set for aligning four parallel rows of cans formovement beneath the vacuum head 16. Alternatively the guide members 17might be arranged to guide two rows of cans or other objects as shownschematically in FIG. 6 (or any number of rows or objects). The vacuumhead 16 is supplied with vacuum through a suitable vacuum pump 26 suchas a Roots AP 24 pump, said pump being driven by suitable motor 27. Theobject or can conveyer 13 is driven by a suitable motor 30.

After the box has moved into the case packer as far as it is going totravel on the conveyer 40, the box is moved leftwardly as viewed inFIGS. 1 and 2 by means of the conveyer 41. Thus, the bars 50 of theconveyer 41 stop the box leftwardly as viewed in FIG. 4 until it ispositioned directly beneath the vacuum head 16. Although only one box isshown in FIG. 4 for claritys sake, a plurality of boxes will be arrangedin order in front of each of the two bars 50 directly to the rear of thebar against which the box is positioned in FIG. 4. Boxes will be fedcontinuously to the conveyer 41 by the conveyer 40.

The conveyer 41 is powered by a hydraulic cylinder (FIG. 9), saidhydraulic cylinder having a piston 116 which extends completely through.the cylinder 115 and is movable between the solid line position of FIG.9 and the dotted line position thereof. A chain 117 is engaged aroundsprockets 120 and 121 rotatably mounted upon the frame 11. The sprocket121 is fixedly secured to a one-way clutch 122 which couples thesprocket 121 and a further sprocket 125 also rotatably mounted upon theframe 11. The further sprocket 125 along with additional sprockets 126(FIGS. 4 and 9) has the chain 47 engaged thereon. As mentioned above,the chain 47 has the bars 50 fixed thereto and is used to step the boxesforwardly to their loading position and out of the apparatus. Thisstepping action is effected by projecting and retracting the piston 116,that is, by moving the piston 116 between the solid and dotted lineposition of FIG. 9.

When the piston 116 is moved from the dotted line to the solid lineposition, there is no movement of the chain 47 because of the freewheeling of the one-way clutch 122. When the piston is moved from thesolid line to the dotted line position, however, the bars 50 areadvanced by the chain 47 one complete position. That is, one of the bars50 moves to the position previously occupied by a next adjacent bar 50.This stepping action is accurately metered by means of a mechanism 130(FIGS. 9 and The mechanism 130 consists of an element 131 swingablymounted on the frame 11 about an axis 132 and a further element 135swingably mounted on the frame 11 about an axis 136. The element 131consists of the two levers 137 and 140 which are fixed together by themember 141. It will be noted that the member 140 has a hook 142 in itsdistal end, said hook cradling the lever 145 forming a part of theelement 135. The element 135 further includes a stop member 146 which isfixed to the lever 145 by the member 147.

Assume now that the cylinder 115 moves the piston 116 from the solid tothe dotted line position. This will also cause the dog 160 fixed to thechain 117 to move rightwardly and to engage the member 161 fixed to thelever 137. Thus, the lever 137 will be moved rightwardly as viewed inFIG. 9 swinging the lever 140 with its hook 142 upwardly forcing thelever 145 upwardly and causing the stop member 146 to swing downwardlyin front of the next bar 50. The dog 160 is so located on the chain 117that it engages the member 161 just prior to the piston 116 completingits stroke. Thus, when the bar 50 engages the stop 146 stopping the bar50 and the chain 47, the piston 116 cannot complete its possible strokeand the pressure in the hydraulic cylinder 115 is relieved by a suitablerelief valve 170 (FIG. 17).

In FIG. 9 the member 161 is shown engaged by a further dog 171. Thisengagement occurs when the piston 116 is completing its strokerightwardly as viewed in FIG. 9 and moving to the solid line position.As mentioned, the chain 47 does not move. When the dog 171 engages themember 161, the stop 146 is moved out of the way of the bar 50 so thatthe next forward movement of the chain 47 is permitted. It will be notedthat when the box 75 is in the position shown in FIG. 4, it is ready forloading by the vacuum head 16. After such loading, the box is steppedleftwardly as viewed in FIG. 4 until it moves off of the surface 51 ofthe carriage 46 and empty boxes are simultaneously stepped into loadingposition. Suitable means for receiving the boxes being stepped off theconveyer should be provided.

CAN CONVEYER The can conveyer 13 includes a belt 200 which is supportedby an elongated support assembly 201 and which rides upon rollers 202and 204. The roller 202 is driven by the motor 30 which operates tocontinually move the upper portion of the belt 200 leftwardly as viewedin FIG. 4. A pan or platform 205 (shown in detail in FIG. 11) is alignedwith and adjacent to the conveyer 13 when the platform is in theposition of FIG. 4. The platform 205 has fixedly mounted thereon a canpattern forming assembly 206 which consists of four vertical plates 207welded to one another to define an open sided configuration. Of course,depending on the number of rows of cans more or less plates 207 might beused. Preferably each case packer is provided with a plurality of theplatforms 205 so that the apparatus can be connected for different canpatterns. The cans are moved onto the platform 205 by the conveyer 13 sothat the four leftward cans in FIG. 6 assume the position shown indotted lines in FIG. 6. Unlike the example shown in FIGS. 1, 2 and 3.the case packer of the remaining figures is shown with only two parallelrows of relatively large cans instead of the four parallel rows forsmaller cans shown in FIGS. 1, 2 and 3.

Referring to FIGS. 6 and 7, the cans which are resting on the conveyer13 must be held in position temporarily while the cans on the platform205 are packed into the box. This holding is accomplished by theholdback mechanism 210 illustrated in FIGS. 6, 7 and 8. The frame 11 hasfixed thereto a horizontal fiat member 211 which has a hydrauliccylinder 212 fixed to its upper surface. Also fixed to the upper surfaceof the member 211 are guide bushings 215 within which guide rods 216reciprocate. The rods 216 and the pistons 217 of the hydraulic cylinder212 are fixed to a channel member 220 (FIG. 4), the channel of whichopens downwardly and receives rollers 221 rotatably mounted upon doorsor gates 222. When the piston 217 of the hydraulic cylinder 212 isprojected, the channel 220 moves the rollers 221 to cause the doors 222to move to a position in alignment with the guide members 17. This isthe position in which the doors are located when the cans are movingonto the platform 205. When it is desired to stop the cans, thehydraulic cylinder 212 retracts its piston 217 causing the doors 222 tomove to the solid line position illustrated in FIG. 6 and in FIG. 8.When the doors move to the position of FIGS. 6 and 8, the containers(jars, bottles or cans) are moved backwards on the conveyer 13. As theconveyers move back in the lanes, they break up any bridging or jammingwhich may form where the con tainers are divided into individual lanes.

It will be noted that the doors have a sufficiently small dimensinbetween their proximal and distal ends so that they can clear the cansalready moved onto the platform. The doors 222 have a sufficiently greatdimension, however, between their distal and proximal ends in order toblock further movement of the cans on the conveyer 13.

Referring again to FIG. 11, the platform 205 has additionally mountedthereon a yoke 350 having a shaft 351 rotatably mounted therebetween. Apair of actuating arms 352 are each rotatably mounted on the rod 351 andare normally retained in an upward position by springs 355. As shown inFIG. 4, the actuating arms 352 extend through apertures 356 inside ofthe pattern forming assembly 206 where the arms 352 can be engaged bythe cans in the pattern. Fixed to the shaft 351 are additional arms 353and 354. The arm 353 has a tension spring 359 connected between it andthe platform 205. The spring 359 is sufiiciently strong to cause thelever arm 360 to move downwardly depressing the actuating arm 361 of theswitch 362 only when the arms 352 are moved out of contact with the arms353 and 354 by a cam pattern in the platform 205. In other words thespring 359 is weaker than each of the individual springs 355.

The platform 205 is movable horizontally by reason of its four rollers400 (FIG. 5) which support the platform in horizontal positions and ridewithin the tracks 401 mounted on the frame 11. The platform 205 is movedby means of a hydraulic cylinder 405 having a piston 406, the distal endof which is pivotally connected to a lever 407. The lever 407 is fixedto a sleeve 410 which is journalled upon the shaft 335. Also fixed tothe sleeve 410 is a lever 411 at the distal end of which is mounted aroller 412 which rides within the vertically extending track 415 fixedto the platform 205. When the piston 406 is retracted, the lever 411 isrotated clockwise as viewed in FIG. 4 causing the platform 205 to moveleftwardly in the tracks 401 and away from the conveyer 13.

A funnel arrangement 420 is provided with vertically spaced rollers 421which ride within the tracks defined by the vertical members 312, inother words, the same tracks within which the rollers 311 ride. Becausethe mounting members 422 upon which the rollers 421 are rotatablymounted are fixed to the funnel, the funnel is movable only in avertical direction. The funnel consists of the frame members 425 and thefunnel elements per se 426 which taper inwardly and are designed toguide the cans into the particular openings 429 in the box 75, saidopenings being defined by the partition 431. The funnel 420 alsofunctions to hold the box in position when loading of the box is beingeffected. The funnel is automatically moved down into the loadingposition when the platform 205 moves away from the position illustratedin FIG. 4 and leftwardly toward the end of the track 401. This automaticmovement is accomplished by means of a pair of cam tracks 430 which arefixedly mounted on the funnel and which slope upwardly and leftwardly asviewed in FIG. 4. The platform 205 has rotatably mounted thereon rollers435 which ride in the cam tracks 430 as the platform moves leftwardly asviewed in FIG. 4. Of course, rightward movement of the platform 205 asviewed in FIG. 4 causes the funnel to be raised from the downwardposition to the upward position shown in FIG. 4.

HYDRAULIC SYSTEM Referring to FIG. 12, there is illustrated thehydraulic system of the present apparatus which includes a hydraulictank 500 and a pump 501. The pump 501 is connected to the relief valve170 through which hydraulic fluid can be returned to the tank throughthe line 502 when the pressure in the line 505 becomes too great.Pressurized hydraulic fluid from the pump 501 is delivered to fourwayvalves 510, 511, 512 and 513 through line 516 and returned to the tankthrough lines 517 and 502. The fourway valves 510, 511, 512 and 513 areactuated by means of respective cams 515, 516, 517 and 518. A furtherfour-way valve 520 is placed in the lines 521 and 522 leading to andfrom the hydraulic cylinder 115 which operates to index the boxesforwardly into and through loading position. The four-way valves 510-513may be, for example, #25P(EE) Gresen hydraulic valves.

The four-way valve 511 controls flow of hydraulic fluid to the hydrauliccylinder 405 which retracts the platform 205. The four-way valve 512controls flow of hydraulic fluid to the hydraulic cylinder 320 whichraises and lowers the vacuum head 316. The four-way valve 513 controlsflow of hydraulic fluid to the hydraulic cylinder 212 which controls thedoors or gates 222. One of the important advantages of the present casepacker is the fact that the indexing of the boxes can be slowed down sothat two or more layers of cams or other objects are packed into asingle box. This is accomplished by causing the four-way'valve 510 tocomplete only one cycle for'every two or more cycles of the four-wayvalves 511 The motor 530 is provided with a sprocket 531 which drives achain 532 Which in turn drives a sprocket 535. The sprocked 535 is fixedto a shaft 536 rotatably mounted on the frame 11. As shown in FIG. 12,the gears 540 and 541 are equal in size and have an equal number ofteeth. These gears can be replaced, however, by a smaller gear for thegear 540 and a larger gear for the gear 541, said replacement gearshaving a two to one gear ratio so that shaft 542 rotatably mounted onthe frame 11 rotates once for each two rotations of the shaft 536. Thecam 515 is integral with a gear 545 which is driven by gear 546 fixed tothe shaft 542. Gear 545 isjournalled on shaft 536 so that cam 515 andgear 545 are freeto rotate at one half the speed of the shaft 536. Thelatter described arrangement is suitable for providing two layers ofcans or objects in a box being. packed. Of course, different replacementgears with the proper gear ratios can replace gears 540 and 541 forpacking three, four, five or more layers.

It should be understood that the intended stroke of the vacuum head 16is down to the box so that the vacuum head carries the first layeralmost all the way into its intended location in the box. When a secondand more layers are packed, the vacuum head 16 stalls out against thefirst and any preceeding layers. In other words, the possible stroke ofthe hydraulic cylinder 320 is not completely used and the relief valve170 prevents the hydraulic pressure from becoming unduly great.

ELECTRICAL CIRCUIT AND OPERATION Various limit switches in addition tolimit switch 362 are provided for sensing the various operatingpositions of the apparatus. Referring to FIGS. 3 and 4, the limit switch362 is located on the side of the case packer adjacent to the platform205 and is mounted on the frame 11. As mentioned, the function of thelimit switch 362 is to indicate when the pattern of cans in the pan orplatform is complete and is ready to be lowered into the box or carton.

A further limit switch 600 (FIGS 4 and 13) is also mounted upon theframe 11 and has its actuating arm positioned to be engaged by a box orcarton is positioned in the loading position. The limit switch 600functions to indicate when the carton is properly positioned in theloading position. A further limit switch 601 (FIGS. 4 and 13) ispositioned at the end of travel of a box moving on the conveyor 40. Thepurpose of the limit switch 601 is to indicate when a carton is inproper position to be indexed by the conveyor 41. A further limit switch602 (FIGS. 7 and 13) is mounted upon the horizontal flat member 211 andhas its actuating arm positioned to be operated by the channel member220. The limit switch 602 indicates or is closed when the gate or doors222 are closed andpreventing further movement of the cans on theconveyor 13. As can be seen in FIG. 13, the limit switch 602 is inparallel with switches 362, 600 and 601 so that during certain portionsof the cycle operation of the switch 602 overrides operation of switches362, 600 and 601.

The electrical circuit of the present mechanism will be described infurther detail in connection with a description of the operation of thedevice. The carriage 46 is adjusted to the proper height by operation ofthe motor 110. As shown in FIG. 13, a reversing switch 605 is providedwhich can be manipulated to cause the motor to raise or lower thecarriage 46. When the carriage 46 is properly adjusted to the desiredheight for the boxes or cartons to be used, the switch 605 is set sothat the motor 110 is turned off. The motor 110 does not operate duringthe case packing cycle. The switch 605 may be a commercially availableAB reversing drum 350 TAV 32 manufactured by the Allen Bradley Companyof Milwaukee, Wis.

The hydraulic pump motor 610 which drives the hydraulic pump 501 is thenturned on by manipulation of the switch 611 connecting the motor 610across the 220 volt three-phase supply lines 612. Hydraulic fluid underpressure is then supplied to the four-way valves 510, 511, 512 and 513.The vacuum pump motor 27 is then turned on by means of the switch 615connecting the motor 27 across the lines 612. Also, the can conveyormotor 30 is started in similar fashion by throwing the switch 616.

A further motor 617 (FIG. 13) is provided for driving the conveyor 40 inorder to move boxes onto the conveyor carriage 46. The motor 617 isconnected across 110 volt lines 620 by closing the switch 621.

At this stage in the operation of the present device, cam 515 is in itsuppermost position having just caused valve 510 to have indexed out afull box. Cam 516 has allowed the valve 511 to force the platform or pan205 to the position illustrated in FIG. 4 adjacent to the conveyor 13.Cam 517 holds valve 512 open so that the vacuum head assembly 16 is inthe raised position of FIG. 4.

A box is placed upon the conveyor 40 and moves into the conveyor 41 intoengagement with the limit switch 601 closing the contacts of the limitswitch. This box or carton is then indexed to the next forward stationon the conveyor 41 by manually operating the hydraulic valve 520. Theabove steps of feeding in cartons on the conveyor 40 and indexing themon the conveyer 41 are repeated until such time as the lead carton is inloading position as shown by the carton 75 in FIG. 4 with the cartondirectly under the platform 205 and under the vacuum head 16. In thisposition, the limit switch 600 is closed by the engagement of the box 75with the limit switch actuating arm closing the contacts of the limitswitch 600.

The operator then throws switch 625 which is in series with the limitswitches 600 and 601 and also in series with the limit switch 362.Closing of the switch 625 does not operate the cam motor 530 until suchtime as the limit switch 362 is closed by the proper forming of apattern of cans on the platform 205. When all of the switches 362, 600and 601 are closed, the cam motor 530 will be operated through thestarting relay 630 and from the 110 volt supply line 620.

When the cams begin to rotate, the cam 518 actuates the actuating arm ofthe four-way valve 513 causing the hydraulic cylinder 212 to retract itspiston 317 and to close the gates 222. This action, as mentioned, breaksup any jams in the cans on the conveyer 13 by backward movement of thecans and also prevents any further movement of the cans off of theconveyer 13. The vacuum head 16 is also caused to descend by operationof the four-way valve 512 through the cam 517 which in turn provideshydraulic fluid to the cylinder 320. The operation of the hydrauliccylinder 212 to retract its piston and to move the channel 220rightwardly also actuates the switch 602, said switch 602 being inparallel with the series connection of switches 362, 600 and 601, thuslocking in the cam motor 530 even though one or more of the switches362, 600 and 601 subsequently opens. The vacuum pump 26 normally exertsvacuum on the vacuum cups 300 except when the vacuum is cut off by theoperation of a suitable valve 650 controlled by the cam 651. The valve650 is caused to shut off vacuum only when the cups 300 release thecans. The cam 517 is so designed as to reverse the four-way valve 512after the cans have been engaged by the vacuum cups so that the vacuumhead raises slightly and lifts the can away from the platform 205.

Just after the cans have been lifted off of the platform, the cylinder405 is caused to move the platform leftwardly as viewed in FIG. 4 by thecam 516 actuating the four-way valve 511. As explained above, suchleftward movement of the platform automatically drops or movesdownwardly the funnel 420 to appropriate position to guide the cans intothe box. When the platform reaches fully retracted position and thefunnel 420 is moved fully downwardly, the cam 517 suitably actuates thevalve 512 to operate the cylinder 320 to lower the pattern of cansthrough the funnel into the carton. At the bottom of the stroke of thevacuum head, the above mentioned vacuum valve is actuated by the cam 651to port the vacuum head to atmosphere and to shut off the vacuum so thatthe can pattern is released into the box. The cam 517 also operates thevalve 512 to cause the cylinder 320 to retract the vacuum head back toits uppermost position. Immediately after the upward movement of thevacuum head out of the way of the platform 205, the cylinder 405 isoperated through the cam 516 and the four-way valve 511 to move theplatform back to the position of FIG. 4. Continued rotation of the camscauses the cam 515 to actuate the cylinder 115 through the four-wayvalve 510 to project the piston 116 from the solid line position to thedotted line position of FIG. 9 indexing the now loaded box 75 leftwardlyfrom the position of FIG. 4 and replacing the now loaded box 75 with anempty box. The cam 515 is so designed that it next operates the four-wayvalve 510 to return the piston 116 from the dotted line position to thesolid line position of FIG. 9.

The final function of the cycle is completed as the gates or doors 222are opened by projecting of the piston 217 of the hydraulic cylinder 212by operation of the four-way valve 513 through the cam 518. The openingof the doors 222 permits the cans to again be moved onto the platform tobegin the filling up of the pattern. When the gates or doors 222 open,the switch 602 is also caused to open which shuts off the cam motor 530so that the cycle cannot be repeated until such time as the threeswitches 362, 600 and 601 are closed by the respective filling of theplatform with cans, proper positioning of the empty box in loadingposition and movement of an empty box on the conveyer 40 into indexingposition for movement on the conveyer 41.

One important advantage found in the use of cams is the fact that thevarious pistons of the hydraulic cylinders can be controlled in such away that they decelerate at the end of their strokes. This feature hasbeen found to make possible much faster overall operation without damageto the machine, boxes and containers being packed.

It will be further evident that the case packer of the present inventionis easily converted so as to deposit any desired number of layers in abox or carton or easily converted to deposit the cans in differentpatterns by use of different platforms and vacuum heads and otheradjustments or easily converted to different sizes of containers andboxes.

The invention claimed is:

1. A case packer comprising a platform in a first position, a frame, anobject conveyer mounted on said frame for conveying objects onto saidplatform, means for moving said platform away from said position, a holdback assembly mounted on said frame and for stopping objects moving onsaid object conveyer while said platform is away from said firstposition, said hold back assembly including vertical parallel guidewalls positioned over said object conveyer and extending in thedirection of movement of said object conveyer for guiding said objectsinto parallel lines, a plurality of vertical doors hingedly mounted onrespective guide walls toward the direction of movement of said objectconveyer, said doors being swingable between a first door position inwhich they extend in alignment with said guide walls and a second doorposition in which they extend perpendicularly to said guide walls andacross said object conveyer, said doors having a dimension between theirproximal and distal ends which is long enough to prevent passage ofobjects between the door and the guide wall toward which it extends butshort enough to permit said doors to swing to said second door positionwithout blocking by said objects.

References Cited UNITED STATES PATENTS 3,052,071 9/1962 Copping 53622,951,574 9/1960 Craig 19830 3,179,230 4/1965 Brown 19s 30 FOREIGNPATENTS 149,284 11/1931 Switzerland.

RICHARD E. AEGERTER, Primary Examiner US. Cl. X.R. 19830

